Help me pleas/ I'll give you brainliest use significant figures rule

6.021cm + 7.4cm + 0.68cm + 12.0cm = ?

10.4168m - 6.0m = ?

1.31cm x 2.3cm = ?

5.7621m x 6.201m = ?

20.2cm ÷ 7.4s = ?

40.002g ÷ 13.000005g = ?

8.41g + 2.067g = ?

5.11g - 0.042g = ?

(4.11 x 10^-6) (7.51 x 10^-4) = ?

8.45 x 10^7 / 6.74 x 10^3 = ?

9.7 x 10^8 / 8.6 x 10^-2​

1)each group 16 element has how many valence electrons? ( )4 ( )6 ( )8 ( )16 2)how many dots appear in the dot structure for calcium ion, ca2+? ( )zero ( )one ( )two ( )eight 3) which of the following atoms forms a cation to obtain an octet of outer shell electrons? ( )magnesium ( )oxygen ( )fluorine ( )helium 4) an al3+ ion contains 13 protons and 10 electrons. ( )true ( )false 5) valence and non-valence electrons are represented in lewis dot structures. ( )true ( )false

Which atom or ion is the largest? a. k b. k+ c. ca d. ca2+ e. li

16. in a reaction that has reached equilibrium, a. the forward and reverse reactions are occurring at the same rate. b. the reactants and products are in equal concentrations. c. the forward reaction has gone further than the reverse reaction. d. there are equal numbers of atoms on both sides of the equation. e. a, b, and d are correct.